This invention relates generally to illuminated indicator systems, and more particularly, to vehicle brake light systems.
All motor vehicles used on public roads are required to have an illuminated brake light system mounted on the rear for indicating to a following driver that brakes have been applied. Ordinarily, electrical energy from a vehicle's electrical supply system is conducted to the brake lights upon closing of a brake switch which is coupled to a brake actuator. An operator of a vehicle, upon actuation of the brake system, simultaneously closes the brake switch which closes an electrical circuit between the vehicle electrical supply and the brake light in the rear. The resulting illumination therefore warns the following driver of impending deceleration. The brake switch may be actuated mechanically or in response to hydraulic forces in a modern brake system.
A variety of studies have been conducted of human responses to indicator lamps. It is now generally accepted that the time that it takes a following driver to respond to a signal is an important factor in traffic safety. In fact, reducing the time period of response, even by a fraction of a second, would result in a significant reduction in the number and severity of rear-end collisions. It is to be noted in this regard that at a vehicle speed of 55 miles per hour (mph), the vehicle is traveling at 80.67 feet per second. It is also to be noted that the filament of an incandescent brake bulb takes approximately 250 milliseconds to reach 90% of its steady-state luminous intensity after the application of 12.8 Volts, which is approximately the voltage of a typical vehicle electrical supply. Thus, a vehicle would travel over 20 feet just in the time required for the brake lamp to reach 90% of its final intensity after application of the brakes.
In addition to the foregoing, it is important to note that significant reductions in the damages which result from vehicle collisions can be achieved for even small increases in the time during which the brakes are applied prior to collision. This results from two important facts. First, the reduction in velocity of a vehicle during braking is proportional to the duration of application of the brakes. Second, the energy of collision is essentially proportional to the square of the relative velocity of the vehicles. Thus, any decrease in the velocity of a collision results in a nonlinear decrease in the energy of the collision. These two characteristics, particularly when combined with one another, result in significant advantages being achieved for only small increases of the duration of the application of the brakes.
Furthermore, stimuli which involves abrupt changes, such as flashing beacons on emergency vehicles, have been used to attract attention more strongly than slowly changing stimuli. This benefit would be especially pronounced in situations in which the perceptual and cognitive loads on a following driver are high, thus placing a premium on drawing his or her attention to high-priority signals.
It is, therefore, an object of this invention to provide a simple and economical system for providing earlier warning to a following driver of a brake application.
It is another object of this invention to provide a luminant indication which increases rapidly with time.
It is also an object of this invention to provide a brake light system having a high luminant output.
It is an additional object of this invention to provide a brake light system which achieves an early indication to a following driver without drawing high energy from the vehicle's electrical supply.
It is a further object of this invention to provide a brake light system which increases lamp life.
It is additionally an object of this invention to provide a brake light system which is more salient than conventional systems.
It is yet another object of this invention to provide a brake lamp system which provides early warning without excessive current draw while using conventional incandescent lamps.